I noticed the warning on the opening screen that the new SIM must be in while unlocking. Is this really necessary? I don't have the new SIM yet because I am mailing this soon-to-be unlocked phone to someone else.

I unlocked my iphone with the previous version of Anysim and, as you are unlocking your phone to be used with all carriers, is not neccesary to have a different sim card that the one that comes with the iphone. Because after the process the phone will be completely unlocked. In case that you are trying to perform only a jailbreak of your phone you will need to use the sim card of the carrier you are trying to use on the phone. Hope it helps you

I unlocked my iphone with the previous version of Anysim and, as you are unlocking your phone to be used with all carriers, is not neccesary to have a different sim card that the one that comes with the iphone. Because after the process the phone will be completely unlocked. In case that you are trying to perform only a jailbreak of your phone you will need to use the sim card of the carrier you are trying to use on the phone. Hope it helps you

You make a good point that since it's completely unlocked, it shouldn't need to have any specific SIM in there while it is unlocking. I'm just really curious why the dev team would put that in the warning screen if it wasn't important...